The reliability of textual transmission

In his article "Unfaithful Transmitters" [1], Patrick Olivelle takes to task those modern philologists who roundly criticize ancient and medieval Indian scholars of the Vedas for introducing changes into the texts, but who then themselves introduce changes, often without noting them, directly into their editions of works. Olivelle in fact shows that the ancient commentators were far more unwilling to introduce changes into the texts, and were also unwilling to impose a Pāṇinian model of correctness (which, in any case, they would have known "a bit better than modern Western scholars," in Olivelle's words) onto the older Vedic text.

Olivelle observes at the end of the article:

"In ancient and medieval India texts were transmitted and preserved by copying onto manuscripts and by memorization, which is a lost art today. The copying of texts introduced errors through negligence or misreading the exemplars and sometimes through deliberate emendations … Error or emendation was limited to a single manuscript and to others for which it served as exemplar … An error or emendation introduced into a printed edition, unlike its manuscript counterpart, is reproduced in every single specimen. Given the expense of publishing, moreover, once an ancient text has been published, it is unlikely that a new edition would be forthcoming soon or ever. The responsibility, therefore, of a modern editor to ensure the faithfulness of transmission is a thousand times greater than that of a scribe."

My including all this context ("con-text"?) was merely a pretext ("pre-text"?) for noting down these two verses with which Olivelle closes his article. They were traditionally written by scribes at the end of manuscripts.

bhagnapṛṣṭikaṭigrīvaḥ stabdhadṛṣṭir adhomukhaḥ |
kaṣṭena likhitaṃ granthaṃ yatnena pratipālayet ||

yādṛśaṃ pustakaṃ dṛṣṭvā tādṛśaṃ likhitaṃ mayā |
yadi śuddham aśuddhaṃ vā mama doṣo na vidyate ||

Olivelle translates them:

With great trouble I have written this book,
My head bent low, with unwavering eyes,
I have broken my back, my hips and neck;
So be diligent and take care of it.

I copied exactly
What I saw in the book;
Whether it's right or wrong,
I am not to be blamed.

On the topic of Vedic memorization, a number of different patterns of recitation (pāṭha) were memorized to eliminate accidental (or deliberate) modification of the text.
1) The standard recitation with sandhi rules applied, and which is what is usually heard in religious contexts, is the saṃhitā-pāṭha.
2) The recitation pattern in which every word (pada) of the Veda is recited individually and separately (but in the same sequence as the saṃhitā-pāṭha) is known as pada-pāṭha.
3) Following this, many increasingly complicated patterns of word-by-word recitation exist, of which the basis is taken to be krama-pāṭha, in which words are recited in pairs: x1; x1 x2; x2 x3 … etc.
4) - 11) The eight variant (aṣṭa-vikṛṭis) pāṭhas built off the krama-pāṭha are defined in a verse:
jaṭā mālā śikhā rekhā dhvajo daṇḍo ratho ghanaḥ |
aṣṭo vikṛtayaḥ proktāḥ krama-pūrvā manīṣibhiḥ || [2]

'Braid', 'garland', 'topknot', 'line', 'banner', 'stick', 'chariot', 'cloud' / 'dense':
The wise speak of the eight variants descending from krama. (My rough translation)

Of these, the ghana-pāṭha, which is so hard that someone who mastered Vedic recitation in this style was awarded the title of ghana-pāṭhin, is as follows:
x1 x2; x2 x1; x1 x2 x3; x3 x2 x1; x1 x2 x3 … [3]

And finally, on the topic of manuscript emendations, a slightly irreverent but nevertheless funny joke that a friend (who shall remain unnamed) once sent:

A new monk arrived at the monastery. He was assigned to help the other monks in copying the old texts by hand. He noticed, however, that they were copying copies, not the original books.The new monk went to the head monk to ask him about this. He pointed out that if there were an error in the first copy, that error would be continued in all of the other copies.

The head monk said, 'We have been copying from the copies for centuries, but you make a good point, my son.' The head monk went down into the cellar with one of the copies to check it against the original.

A few minutes later, there was a gasp from the cellar. The new monk ran downstairs to find the head monk, pale and shaking, staring at one of the original texts in horror.

"What's wrong?" the new monk demanded.

"Celebrate?!? It says CELEBRATE?!?"

< UPDATE >

I learned only today while reading Don Davis' The Spirit of Hindu Law that the word vikṛti, which I translated above as "variant", is in fact a technical term that derives from the earliest accounts of Vedic ritual. Apparently the universe of the Vedic ritual is structured around a single archetypal sacrifice, with all others being derived as ectypes of this one sacrifice. Of course, substantially complicated sacrifices often become archetypes of their own, but everything is ultimately dependent on the one basic archetype. The archetype-ectype distinction is noted in the ritual handbooks by the dyad prakṛti-vikṛti. The great benefit of structuring the ritual universe this way was that scholars only had to give detailed accounts of archetypal units; for the ectypes, it would then suffice to merely note the differences from the archetype.

Because of its compactness, this Vedic structuring principle was heavily utilized in other spheres of intellectual activity, including jurisprudence (where the idea of debt and its repayment is the archetype from which everything is explained), Vedic recitation (as shown above, where the krama-pāṭha is the archetype for the aṣṭa-vikṛtis), and social dharma (where the rights and responsibilities of the Brahmin male form the archetype for all of society). Indeed, this structure is so pervasive that the ritual handbooks' use of the prakṛti-vikṛti dyad must itself be seen as a prakṛti for all other ectypal uses of the dyad in other spheres of intellectual activity!

< /UPDATE >

References
[1] Olivelle, Patrick. "Unfaithful Transmitters: Philological Criticism and Critical Editions of the Upaniṣads." Journal of Indian Philosophy 26: 173–187, 1998. Accessible here.

[2] Abhyankar, Kashinath Vasudev and J. M. Shukla, A Dictionary of Sanskrit Grammar (Baroda: Maharaja Sayaji Rao University of Baroda, 1986).

[3] Apte, Vaman Shivram. The Practical Sanskrit-English Dictionary. Accessible here.